Substantial commerce has been built about the cleaning of surfaces, and particularly textile fabric surfaces such as carpet, upholstery and the like, by the practice of methods and the use of apparatus characterized as liquid spray and vacuum pick-up methods and apparatus. Examples of such methods and apparatus may be found in Emrick et al U.S. Pat. No. 3,883,301 issued May 13, 1975 and Williams et al U.S. Pat. No. 4,069,541 issued Jan. 24, 1978. To the extent that the disclosures of those prior patents are appropriate or necessary to a full understanding of the present invention, the disclosures to be found there are hereby incorporated by reference into the present specification.
Commercial activity using the methods and apparatus as known heretofore has included two major fields. First, homeowners and others may, from time to time, rent apparatus offered through rental locations such as hardware stores, dry cleaning establishments and the like. Such rental apparatus is used for "do it yourself" cleaning of carpet and the like in a homeowner's residence or the like. In the past, substantially similar apparatus has been used by commercial carpet cleaners who sell services as distinct from renting apparatus. Typically, such a commercial carpet cleaning service may be hired by the owner of a public building for cleaning carpet used in such a building, although commercial cleaning services also offer household carpet cleaning services in competition with machine rentals for "do it yourself" homeowners.
As such commerce has developed, it has become important to the operator of a commercial carpet cleaning service that the cleaning apparatus used facilitate achieving optimal cleaning. That is, commercial carpet cleaning services are conventionally priced on a unit area basis. Thus, while a "do it yourself" homeowner may be willing to spend substantial time cleaning or attempting to clean a specific area, a commercial carpet cleaning service has as an objective the efficient cleaning of the area with a minimum expenditure of time.
One problem faced by both the homeowner and the commercial carpet cleaning service is the differing dirtiness of carpet in heavy traffic and low traffic areas. As is known, any path across a carpeted area which carries heavier traffic becomes more dirty. Thus, a person cleaning the carpet is faced with carpet areas of differing dirtiness and cleaning techniques must be adapted to the varying needs. Heretofore such adaptation of cleaning techniques has included the use of more powerful cleaning agents known as traffic spotters and more concentrated effort for longer intervals of time in use of the cleaning apparatus employed.